1. Field of the Invention
A method of manufacturing a compressor or fluid motor generally classified in Class 29, Subclass 156.4R.
2. Description of the Prior Art
U.S. Pat. No. 1,548,382 (J. A. Paul) discloses a piston and connecting rod connection which permits adjustment between the crown of the piston and the center line of the bearing engaging the crankshaft. This patent does not disclose the cast-in-place technique for either the piston to connecting rod joint, or the connecting rod to swash plate joint, and further does not even disclose a swash plate.
U.S. Pat. No. 2,107,795 (E. P. Larsh) discloses a two piece connecting rod in which the portion of the rod connected to the piston comprises a tube which fits telescopically over a shank portion of the connecting rod bearing section. This disclosure is has the same shortcomings as the Paul patent.
U.S. Pat. No. 2,252,351 (W. Paulus) is one of the earliest disclosures of a cast-in-plate technique for forming a ball and socket connection between two parts.
U.S. Pat. No. 3,763,535 (Gallagher) is directed to a method of forming a ball and socket connection between a connecting rod and a piston. The purported novelty concerns the use of a selected pressure for the molten material introduced into the mold cavity during the die casting process.
3. Additional Background Description
In the past ball and socket assemblies are used extensively to allow combinations of axial, rotational and orbital movements in machinery. Such machinery components include pistons, drive plates and crank shafts in pumps and compressors, actuating toggles for presses and punches, connecting rods and assemblies in conveyor systems. These components are eminently suitable for use in swash plate assemblies, such as the assembly of this invention.
Depending on the accuracy and/or strength required of the ball and socket joint, there are several methods for constructing the assembly. For example, a round aperture with a spherical bottom can be machined into the socket member. This requires accurate and expensive tooling. After the ball with its stem or other attachment is placed into the aperture, the wall of the aperture must be made to enclose the ball to retain it in the socket during its motion. The enclosing can be accomplished by rolling, swaging, pressing, spinning or any other suitable metal deforming process where the aperture wall is deformed to conform around the ball to the degree required for strength of the joint and to allow the required freedom of movement. Each of these presently used enclosing procedures is a separate operation in manufacture of the assembly. The procedure selected depends on economy, degree of accuracy or tightness required of the joint, and also on the materials of construction of both ball and socket.
To produce strong assemblies, capable of withstanding repeated heavy loads or to produce precise assemblies with a controlled or minimum movement or "play" between the ball and socket, a maximum amount of comformity of the ball to socket must be achieved. This high degree of conformity requires large deformations of the socket material which requires more time consuming and expensive procedures and equipment. The maximum "fit" also demands a large degree of deformation of the socket material which may require the use of soft, weak material by necessity, but which may still result in cracking or stresses that act to further weaken the assembly.
The high pressures required to deform the walls of the aperture to conform to the ball imposes the requirement that the ball be made of a high strength material that will resist crushing during forming. This limits the selection of ball materials with possible penalties in desired properties or economy.
Aside from the problems cited above, the high pressures of forming do not assure full socket conformity to the spherical surface of the ball. As a result of incomplete forming, and also because of wrinkling and buckling of the deformed materials, the applied loads are not uniformly distributed over the spherical surface of the ball. This results in concentrated loads which cause overloading and failure. Such load concentrations also cause excessive wear on the contact points, which increases the amount of relative movement in the socket and thus complicates loading, leading to premature failure.
Any and all of the methods of assembling the ball to the socket are such that precise dimensions of the assembly cannot be maintained. In many applications, two or more ball socket joints are connected to form the piece of machinery. Final dimensioning of the apparatus must be performed by machining of the unwieldy assembly.
In many of the mechanical forming processes, a spacer material or coating is applied on either the ball or on both components, to assure that some, or a specified amount, of relative movement will exist between the components. Such "spacers" must be removed by dissolving, heating or mechanical means.
Other methods of forming the ball socket assembly include the use of wires, rods or pins which prevent the escape of the ball from the socket. These require secondary operations to fix the retainer to the socket body. Another method would be to machine spherical apertures into two separate sections, and then connect the separate sections after enclosing the ball. The connecting could be by fasteners, springs, brazing, etc.